Be jealous and desperate.

"Dua, you are really attracted to him...but know that he's mine."
Taylor gives you a smile.
You smile back.

"You will want him. You will need him.
When we ignore you, you will get desperate and offer to do more things for him to give you attention."

You whisper a suggestion into her ear.
Taylor gives you a look...and then a sly smile.

"You will also offer to do stuff for me...and to me to get your chance. You will know that he will never belong to you...but you might be able to borrow him."

Dua is awakened and sees you and Taylor making out.
The Singer needed no prompting for this.

"May I....may I...join you," Dua mutters, super shy all of a sudden.

You both ignore her and she blushes.

Desperate, she strips off the rest of her clothes and puts her hands behind her back.

"I'll all yours. Please take me."

You keep ignoring her, both of your respective hands fondling the other.

She gets on her knees and begs now.

You begin to fondle Taylor's right breast and this inspires Dua.

"I'll...pleasure you, Taylor...if you let me have him...just for a while."

You stop kissing and share a look.